Detecting the end of cycling activities on a wearable device

Abstract

Disclosed embodiments include wearable devices and techniques for detecting cycling activities and monitoring performance during cycling. By accurately and promptly detecting the end of cycling workouts automatically, the disclosure enables wearable devices to accurately calculate user performance information when users forget to stop recording a cycling activity session. In various embodiments, cycling activity detection techniques involve a cycling speed measure that incorporates terrain gradient determined based on pressure data. In various embodiments, the cycling activity detection techniques may distinguish between a temporary stop and an intentional stop using an estimated energy expenditure.

1 . A method for improving performance of a wearable device while recording a cycling activity, the method comprising:
 starting a cycling activity;   receiving motion data of a user from a motion sensing module of the wearable device;   measuring, by a heart rate sensing module of the wearable device, a heart rate of the user, the heart rate sensing module comprising a photoplethysmogram (PPG) sensor configured to be worn adjacent to the user's skin;   calculating, by the one or more processor circuits, the user's performance information during the cycling activity, the performance information including a mechanical work rate and an energy expenditure rate; and   detecting, by the one or more processor circuits, an end of the cycling activity, the detecting the end of the cycling activity comprising:   comparing the mechanical work rate to a mechanical work rate threshold;   in response to detecting a value for the mechanical work rate above the mechanical work rate threshold, calculating a difference between the mechanical work rate and the energy expenditure rate; and   determine the end of the cycling activity based on the difference between the mechanical work rate the energy expenditure rate.   
     
     
         2 . The method of  claim 1 , comprising:
 receiving location data from a GPS module of the wearable device, the location data including a user speed of travel during the cycling activity;   receiving atmospheric pressure data from a pressure sensor of the wearable device; and   calculating the mechanical work rate based the location data, the atmospheric pressure data, and the motion data.   
     
     
         3 . The method of  claim 1 , wherein the mechanical work rate threshold is consistent with light exercise. 
     
     
         4 . The method of  claim 2 , comprising:
 detecting, by the one or more processor circuits, a stop during the cycling activity, the detecting the stop comprising:   receiving a value for the user speed of travel below an expected cycling speed; and   receiving a motion data characterized as non-cycling motion.   
     
     
         5 . The method of  claim 4 , comprising:
 estimating an energy expenditure rate at two or more points during the cycling activity based on the user heart rate;   calculating a difference between a first energy expenditure rate estimated before the stop was detected and a second energy expenditure rate estimated after the stop was detected; and   detecting an intentional stop based on the difference between the first energy expenditure rate and the second energy expenditure rate.   
     
     
         6 . The method of  claim 5 , comprising:
 upon detecting the intentional stop, ending the cycling activity and terminating calculation of the user's performance information. The method of  claim 5 , comprising:   upon detecting the intentional stop, sending a confirmation request to a user to confirm the end of a cycling activity.   
     
     
         8 . The method of  claim 5 , comprising:
 detecting a temporary stop based on the difference between the first energy expenditure rate and the second energy expenditure rate; and   maintaining the cycling activity in response to detecting the temporary stop.   
     
     
         9 . The method of  claim 2 , comprising:
 receiving a value for the user speed of travel within an acceptable range for an expected cycling speed and motion data characterized as a cycling motion; and   identifying a driving activity based on the difference between the mechanical work rate the energy expenditure rate.   
     
     
         10 . The method of  claim 9 , wherein the difference between the mechanical work rate and the energy expenditure rate is equivalent to the mechanical work rate minus an energy expenditure rate consistent with light exercise. 
     
     
         11 . The method of  claim 10 , further comprising: in response to detecting the driving activity,
 ending the cycling activity, and   stopping calculation of performance information.   
     
     
         12 . The method of  claim 2 , wherein the user speed of travel is calculated, by the one or more processor circuits, from GPS positioning data received from the GPS module. 
     
     
         13 . The method of  claim 2 , comprising:
 receiving the atmospheric pressure data from the pressure sensor of the wearable device;   determining, by the one or more processor circuits, a grade describing a measure of steepness of terrain cycled on during the cycling activity; and   calculating, by the one or more processor circuits, elevation gained during the cycling activity using the grade.   
     
     
         14 . The method of  claim 13 , comprising:
 detecting, during the cycling activity, a stepping motion within the motion data, wherein the stepping motion is distinct from a pedaling motion;   extracting user steps included in the stepping motion using a user step model;   based on user steps and the grade, determining mechanical work performed during the stepping motion; and   incorporating mechanical work performed by the user during the stepping motion into the mechanical work rate.   
     
     
         15 . The method of  claim 14 , wherein the performance information comprises at least one of an overall distance traveled, a total cycling time, a speed, the elevation gained, a power output, and a number of calories burned. 
     
     
         16 . A method for improving performance of a wearable device while recording a cycling activity, the method comprising:
 starting a cycling activity;   receiving motion data of a user from a motion sensing module of the wearable device;   measuring, by a heart rate sensing module of the wearable device, a heart rate of the user, the heart rate sensing module comprising a photoplethysmogram (PPG) sensor configured to be worn adjacent to the user's skin;   calculating, by the one or more processor circuits, the user's performance information during the cycling activity, the performance information including a mechanical work rate and an energy expenditure rate; and   detecting, by the one or more processor circuits, an end of the cycling activity, the detecting the end of the cycling activity comprising:
 comparing the mechanical work rate to a mechanical work rate threshold; and 
 in response to detecting a value for the mechanical work rate below the mechanical work rate threshold, ending the cycling workout and stopping calculation of the user's performance information. 
   
     
     
         17 . The method of  claim 16 , comprising:
 generating, by the one or more processor circuits, a notification including a request to end the cycling workout, the notification displayed on a display of the wearable device.   
     
     
         18 . The method of  claim 16 , wherein the motion data includes a step speed estimating a frequency of the user's lower body movements while performing pedal strokes during the cycling activity. 
     
     
         19 . A system for improving performance of a wearable device while recording a cycling activity, the system comprising:
 a motion sensing module configured to collect a user's motion data;   a heart rate sensing module configured to measure a heart rate of the user, wherein the heart rate sensing module comprises a photoplethysmogram (PPG) sensor and the PPG sensor is configured to be worn adjacent to the user's skin;   one or more processor circuits in communication with the motion sensing module and the heart rate sensing module, wherein the one or more processor circuits are configured to execute instructions causing the processor circuits to:
 start a cycling activity; 
 calculate the user's performance information during the cycling activity, the performance information including a mechanical work rate and an energy expenditure rate; 
 compare the mechanical work rate to a mechanical work rate threshold; 
 in response to detecting a value for the mechanical work rate above the mechanical work rate threshold, calculate a difference between the mechanical work rate and the energy expenditure rate; and 
 detect an end of the cycling activity based on the difference between the mechanical work rate and the energy expenditure rate. 
   
     
     
         20 . The system of  claim 19 , further comprising:
 a GPS module configured to measure location data including a user speed of travel during the cycling activity;   a pressure sensor configured to measure atmospheric pressure data; and   wherein the processor circuits are further configured to:
 receive the location data and the pressure data; and 
 calculate the mechanical work rate based the location data, the atmospheric pressure data, and the motion data.